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are found to be parallel. The pillars are made as fhort as 

 pofTible ; to favour which, the frame M has a furrow cut in 

 the middle of it under the wheel I, to let the teeth of the 

 wheel defcend almoft to the table on which the machine refts ;. 

 and the pump barrel is placed as near as may be to the 

 rack. 



On the upper part of the box containing the collar of leathers, 

 is a projeding part of the metal, in the fhape of a cube, forming a 

 little pedeftal O,: on this is placed the valve f; from beneath 

 which defcends a ftraight dud into the barrel without penetrating 

 the box : the form of the parts of this valve (all made of brafs 

 and of the fize of the originals belonging to the pump) is re- 

 prefentcd in fig. 4. in a vertical fedion. A A is a fquare plate 

 (to be taken off, if it fliould require to be ground and polifhed 

 anew in contad with the valve ;) which is faftcned on the pedef- 

 tal with cement ; it has a hole in the middle, being the open- 

 ing of the dud, in which is inferted the little elevated pipe c, 

 to be occafionally taken out ; whofe ufc is, to prevent the oil 

 applied to the valve from being blown down into the dud, by 

 the air rufhing into the barrel : the elevated part of the plate 

 a a is circular, and has its upper furface made plane and po- 

 lidied, on which refts the valve D ; which is fo far hollowed 

 within, that only its lower edge, being about y-s-th of an inch 

 thick, (which is alfo well polifhed) may be in contad with the 

 plate under it, and alfo that its cavity may rife above the little 



pipe : 



